Hypotension of the inferior esophageal sphincter is due to a variety of causes and results in gastroesophageal reflux and esophagitis. A number of "sphincter enhancing" operations are currently available to restore normal pressure at the high pressure zone (HPZ) including posterior gastropexy (Hill), Mark IV (Belsey), and fundoplication (Nissen). It is not known which of these is most effective. Randomized clinical studies are unavailable and laboratory studies have been concerned with either postmortem specimens or an unsuitable laboratory animal (dog). The purpose of this study is to study the effectiveness of the above mentioned procedures in restoring the HPZ in the cat, whose inferior esophageal sphincter has been rendered hypotensive by myomectomy. The results of the experimental procedures will be monitored by cinefluorography, esopheal manometry, pH reflux tests and postmortem pathologic studies, and may be applicable to the selection of a proper procedure for use in man.